New Type of Defects Explored by Theory: Silicon Interstitial Clusters in SiC

Abstract

We have studied the small clusters of silicon and carbon interstitials by ab initio
supercell calculations in 4H-SiC. We found that silicon interstitials can form stable and electrically
active complexes with each other or with a carbon interstitial. Local vibration modes and
ionization energies were also calculated in order to help the identification of the defects. We
propose that silicon interstitials can emit from these clusters at relatively high temperatures,
which may play an important role in the formation of the DI center.